Various attempts have been made to address the problem of how to scroll or advance virtual sheet music for a user playing an instrument or singing a song, who is watching the musical notes from a score on a display screen. The need for a system that advances or scrolls the musical notes in a synchronized manner that corresponds to the real-time tempo of the user who is actually playing or singing the music is even more important with the advent of personal digital assistants, portable reader devices, and cell phones containing smaller displays that are highly portable.
U.S. Pat. No. 7,482,529 describes a self-adjusting music scrolling method, which comprises providing a display screen, selecting a music score to be played by a musician, wherein the music score is cataloged and stored in a music score database as a first MIDI file, displaying a first portion of the selected music score on the display screen, recording musical notes played by a musician with a digital device, storing the recorded musical notes in memory as a WAV file, converting the WAV file into a second MIDI file, comparing the first MIDI file and the second MIDI file with a MIDI comparison algorithm, determining if the first MIDI file substantially matches the second MIDI file, automatically adjusting the music score on the display screen to show a second portion of the selected music score upon determining that the first MIDI file substantially matches the second MIDI file, and displaying one or more mistakes detected on the display screen upon determining that the first MIDI file does not substantially match the second MIDI file.
U.S. Pat. No. 5,760,323 describes an electronic display stand that can advance through musical notes without interrupting a musician's performance. The stand can be controlled by remote mechanical actuation, the sound of musical notes (note detection), or a timed interval. The device can have a display large enough to display a full page of sheet music at one time. A plurality of the devices can be networked to simultaneously display musical notes to a number of musicians.
Software exists for karaoke systems that displays lyrics of a song where each word is highlighted in time to the melody so a singer can devote the correct amount of time for each word. For example, see MIDI Master Karaoke 3.5 described at http://www.supershareware.com/info/midimaster-karaoke.html.
In addition, software exists in connection with Karaoke systems for analyzing pitch of a singer's performance, in which a melody guide is graphically displayed, matching what the user must sing. With a microphone, the software analyze the user's singing and computes a score. For example, see http://www.idolmusicstar.com/en/index.php.
Also, software exists for detecting beats per minute from a musical sample. For example, see Beat Monitor at http://www.sharewareconnection.com/beat-monitor.htm. Another example is U.S. Pat. No. 6,518,492, which describes software for detecting beats per minute from a digitized or live musical sample.